Moving pictures are captured using equipment that records a sequence of static images that, when displayed in sequence, create the appearance of motion. The rate at which the static images are captured is known as the frame rate. There are many standards defining the frame rates commonly used in film-making and television. In the United States, film is commonly captured at a rate of 24 frames per second (fps) or Hertz (Hz). At this rate, motion is captured adequately, and allows for creative expression due to a slow rate of image change. However, if viewed at this rate in a system designed to be viewed at a higher frame rate, the moving image may appear choppy. Video capture, as opposed to film, generally records images at a rate of 50 to 60 fps.
Video processing and display devices may receive input signals representing motion pictures captured at different frame rates. Additionally, processing may have occurred to the signal prior to it reaching the device whereby the received signal is converted to a different frame rate than the frame rate at which the original source was captured. In either case, the input signals must be processed and the signal to be displayed must be converted to a frame rate appropriate for the display device. When the frame rate needs to be increased, the frequency of the sequenced images may be increased by repeating frames a certain number of times. While this does not accurately reproduce the true motion of the subject of the image, it may allow the viewer to perceive the video with less flickering, on some types of display devices. Additionally, frame rate conversion processing may include analysis of changes from one frame to the next at a pixel level to create estimates of the motion within the image and thereby allow intermediate frames to be synthesized, to enhance the perception of motion.
It is becoming increasingly popular to convert video images from 50 or 60 Hz to 100 or 120 Hz to get much higher frame rates. This can reduce the motion blur problem inherent in those LCD displays which use a fluorescent backlight. When images are displayed on such LCD displays at a higher frame rate, there is a psycho-visual phenomenon occurring within the brain of the viewer where the appearance of blurring is lessened. Achieving motion blur reduction in this way requires motion compensated frame rate conversion.
Occasionally, an input signal will include image capture information from more than one original source. An example of this is picture-in-picture where a video image is displayed as background with a second video image being inset into the first video image so that both motion pictures can be viewed simultaneously. In order to do this, the multiple input signals must be combined into a composited signal containing both sequences of images. This composited image must be converted to a single frame rate regardless of the frame rates at which each of the original images was captured. In present frame rate conversion systems, such conversions may exhibit undesired visual artifacts when attempting to display the composited image after frame rate conversion. These systems lose information about each of the input signals when the signals are combined in the compositing and scaling process. Such information could be used by the frame rate converter when creating frame rate conversion decisions. Therefore it would be beneficial to have a system where the data regarding input video signals is generated and transmitted to the frame rate converter processor along with the signal for use by the frame rate converter to create a final output video image.